When a chemical reaction is at equilibrium, which of the following statements is always true?
a. the equilibrium constant keq= 1.
b. the ratio of the concentrations of reactants and products equals 1.
c. the rate of the forward reaction is equal to the rate of the backward reaction.
d. all of the choices are correct.

The correct answer is Option D.

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric coefficients. It is represented by

For a general chemical reaction:

The is written as:

There are 3 conditions:

At equilibrium, the  ratio of concentration of reactants to the concentration of products is equal to 1.

At equilibrium, the rate of forward reaction is equal to rate of backward reaction.

Hence, the correct answer is Option D.

the answer is true.